Button Fastener and Button Structure

ABSTRACT

The button fastener comprises a fastener body and a cover member which is attached to the fastener body. The fastener body includes a disk-like base and a hollow, cylindrical post extending upward from a center area of the base concentrically. The post has a top opening at its upper end and a bottom opening in a center area of the base. The cover member covers the lower surface of the base including the bottom opening. The base includes a base bottom adjacent to the post and a base flange rising upward relative to the base bottom radially outward from the base bottom. The cover member includes a curved outer periphery curving from the lower surface side of the base and then rising upward beyond the base flange of the base.

BACKGROUND OF THE INVENTION

This invention relates to a button fastener and a button structure, andmore specifically, to a button fastener to fasten a button such as adecorative button, a snap button to a fabric, and a button structurecomposed of a button and a button fastener.

As a combination of a button and a button fastener to fasten the buttonto a fabric, a type has been known where a button is fastened to afabric by deforming and fixing a post of a button fastener within apost-receiving space or an inside space of a projection of the button,after the post has pierced the fabric to be received in the space, asshown in Japanese Examined Utility Model Application Publication No.S60-8724, Japanese Published Patent Application No. 2005-204911. Asexamples of such a button, there are a decorative button, which isfastened to e.g. corners of a pocket of jeans, and a male snap of a snapbutton, which is mounted to e.g. parts of clothes to be put together. Ina state of a button having been mounted onto a fabric, the fabric isheld between a flange of the button and a base of the button fastener.

However, with conventional buttons and button fasteners, when a fabricis thin, it would be unable to firmly hold the fabric between the flangeof a button and the base of a button fastener, and there would be a casethat a button cannot be surely fastened to a fabric. Further, as a postof a button fastener pierces a fabric to fasten a button to the fabric,a round piece of the fabric arises. With common button fasteners, thepiece would go into the post-receiving space of the button, which couldhamper a deformation of the post, have an adverse effect on theconnection between the button and the button fastener, and necessitatean additional work to remove fabric pieces after a button mounting work.

[Patent Document 1] Japanese Examined Utility Model ApplicationPublication No. S60-8724

[Patent Document 2] Japanese Published Patent Application No.2005-204911

An object of the invention as made in view of the above-mentionedproblems is to provide a button fastener and a button structure whichcan surely fasten a button to a fabric even if the fabric is thin.

Another object of the invention is to provide a button fastener and abutton structure in which fabric pieces, which arise at the time offastening the button to the fabric, do not have an adverse effect on thebutton-fastening, and a work to remove fabric pieces is unnecessary.

SUMMARY OF THE INVENTION

To solve the problems, according to the present invention, there isprovided a button fastener for fastening a button to a fabric,comprising: a fastener body including a disk-like base and a post whichextends upward from a center area of the base concentrically; and acover member which is attached to the fastener body so as to cover thelower surface of the base; wherein said base includes a base bottomadjacent to the post and a base flange rising upward relative to thebase bottom radially outward from the base bottom; wherein said covermember includes a curved outer periphery curving from the lower surfaceside of the base and then rising upward beyond the base flange of thebase.

In the invention, when the button is being fastened to the fabric, thefabric is held between the button and the curved outer periphery of thecover member of the button fastener. Here, since the curved outerperiphery of the button fastener lies upward further than the baseflange which rises upward in the base of the fastener body, the intervalbetween the button and the curved outer periphery which face each otherholding the fabric therebetween at the time of fastening the button canbe narrower, which makes it possible to surely fasten the button to athinner fabric.

In an embodiment of the invention, said post is hollow and cylindricaland includes a top opening which is open at the upper end of the postand a bottom opening which is open in a center area of the base. Whenthe button is fastened to the fabric, the post of the button fastenercuts and pierces the fabric bringing about a round piece of the fabric.This fabric piece can be taken in the interior of the post through itstop opening, so the fabric piece could not hamper a deformation of thepost. Further, since the cover member covers the lower surface of thebase of the fastener body closing the bottom opening, the fabric piece,which has arisen at the time of fastening the button to the fabric, isnot discharged out of the post through the bottom opening, stayingwithin the post after it is captured in the post.

The fastener body and the cover member in the invention can be formedsuch as by drawing a metal plate of e.g. aluminum, iron, stainlessalloy, copper alloy including brass.

In an embodiment of the invention, said upper end of the post is formedas an edge which is able to cut the fabric against the button when thebutton is fastened to the fabric. By making the upper end of the post anedge, the fabric can be cut and pierced by the post smoothly.

In an embodiment of the invention, said post includes a fold-backportion which is folded back radially inward and downward from the upperend of the post. The fold-back portion can serve to reinforce an upperpart of the post and to enhance the effectiveness of the edge at theupper end of the post.

In an embodiment of the invention, said fold-back portion includes, onits inner periphery, a first inclined surface which gently inclinesradially inward and downward from the upper end of the post and a secondinclined surface which steeply inclines radially inward and downwardfrom the radially inner end of the first inclined surface. The firstinclined surface forms the top edge together with the outer peripherysurface of the upper part of the post. In addition, at the timeimmediately before the edge of the post cuts the fabric, the firstinclined surface can hold the posture of the fabric while pressing thefabric against the button side, enhancing the effect of the edge andserving to help cut the fabric smoothly.

In an embodiment of the invention, said post includes a post proximalportion adjacent to the base, a post distal end including the upper end,and a post barrel portion linearly extending between the post proximalportion and the post distal portion, wherein the outer diameter of thepost distal portion expands radially outward from the upper end of thepost barrel portion, and the maximal outer diameter of the post distalportion is greater than the outer diameter of the post barrel portion.In this way, by expanding the post distal portion radially outwardrather than the post barrel portion, the top opening enlarges so thatthe fabric piece cut out by the upper end of the post at the time offastening the button to the fabric can be easily captured into the post.

In an embodiment of the invention, the thickness of the post barrelportion, post distal portion and fold-back portion is gradually thinnerfrom the lower end to the upper end of the post barrel portion, andthen, via the post distal portion, from the upper end to the lower endof the fold-back portion, except for about the upper end of the post asthe turn-round part of the fold-back portion. In this way, by graduallythinning down the post barrel portion, the post distal portion and thefold-back portion in this sequence, a load as needed to turn down thefold-back portion can decrease compared with a constant thickness.

According to the second present invention, there is provided a buttonstructure composed of a button and a button fastener for fastening thebutton to a fabric, the button fastener comprising: a fastener bodyincluding a disk-like base and a post which extends upward from a centerarea of the base concentrically; and a cover member which is attached tothe fastener body so as to cover the lower surface of the base; whereinsaid base includes a base bottom adjacent to the post and a base flangerising upward relative to the base bottom radially outward from the basebottom; wherein said cover member includes a curved outer peripherycurving from the lower surface side of the base and then rising upwardbeyond the base flange of the base; wherein said button includes aprojection projecting upward and an annular flange extending radiallyoutward from the projection; wherein said projection defines apost-receiving space in the interior thereof for receiving, deformingand fixing the post which has pierced the fabric; wherein said flange,in the state where the button has been fastened to the fabric with thepost fixed in the post-receiving space, faces the curved outer peripherywith the fabric held between the flange and the curved outer periphery.

In the invention, when the button is being fastened to the fabric, thefabric is held between the flange of the button and the curved outerperiphery of the cover member of the button fastener. Here, since thecurved outer periphery of the button fastener lies upward further thanthe base flange which rises upward in the base of the fastener body, theinterval between the flange of the button and the curved outer peripherywhich face each other holding the fabric therebetween at the time offastening the button can be narrower, which makes it possible to surelyfasten the button to a thinner fabric.

In an embodiment of the invention, said post is hollow and cylindricaland includes a top opening which is open at the upper end of the postand a bottom opening which is open in a center area of the base. Whenthe button is fastened to the fabric, the post of the button fastenercuts and pierces the fabric bringing about a round piece of the fabric.This fabric piece can be taken in the interior of the post through itstop opening, so the fabric piece could not hamper a deformation of thepost. Further, since the cover member covers the lower surface of thebase of the fastener body closing the bottom opening, the fabric piece,which has arisen at the time of fastening the button to the fabric, isnot discharged out of the post through the bottom opening, stayingwithin the post after it is captured in the post.

In the inventions, the button fastener comprises the fastener body andthe cover member, and the curved outer periphery of the cover memberlies upward further than the base flange which rises upward in the baseof the fastener body, the interval between the curved outer periphery ofthe button fastener and (the flange of) the button which hold the fabrictherebetween in the state where the button has been fastened to thefabric, which makes it possible to surely fasten the button to a thinnerfabric.

Further, since the fabric piece, which arises as the post of the buttonfastener cuts and pierces the fabric when the button is being fastenedto the fabric, can be taken in the interior of the post through its topopening, the fabric piece could not have an adverse effect on adeformation of the post and the connection between the button and thebutton fastener. Furthermore, in the button fastener, since the covermember covers the lower surface of the fastener body including thebottom opening of the post, the fabric piece, which has been taken inthe interior of the post through of the top opening of the post, is notdischarged out of the post, a work to remove fabric pieces isunnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a button fastener in accordance with anembodiment of the present invention.

FIG. 2 is a longitudinal sectional view of FIG. 1.

FIG. 3 is an illustrative longitudinal sectional enlarged view showingthe post distal portion and the fold-back portion of the buttonfastener.

FIG. 4 is an illustrative cross-sectional view showing a state where thebutton and the fabric are arranged with respect to the fabric.

FIG. 5 is an illustrative cross-sectional view showing a stateimmediately before the fabric is cut by the button fastener in thebutton-fastening process.

FIG. 6 is an illustrative cross-sectional view showing a stateimmediately after the fabric is cut by the button fastener in thebutton-fastening process.

FIG. 7 is an illustrative cross-sectional view showing a state where thebutton fastener is being deformed in the button-fastening process.

FIG. 8 is an illustrative cross-sectional view showing a state where thebutton-fastening is completed after the button fastener is deformed inthe button-fastening process.

FIG. 9 is a longitudinal sectional view showing a button fastener inaccordance with another embodiment of the present invention.

FIG. 10 is a longitudinal sectional view showing a button fastener inaccordance with another embodiment of the present invention.

FIG. 11 is a longitudinal sectional view showing a button fastener inaccordance with still another embodiment of the present invention.

FIG. 12 is an illustrative sectional view, similar to FIG. 8, showing anexample using another type of a decorative button as a button.

FIG. 13 is an illustrative sectional view, similar to FIG. 8, showing anexample using a male snap as a button.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the invention will be describedwhile referring to the drawings. FIGS. 1 and 2 are a perspective viewand a longitudinal sectional view of a button fastener (hereinafterreferred to also as “fastener”) 1 in accordance with an embodiment ofthe present invention. The fastener 1 comprises a fastener body 10 and acover member (shell) 40, each of which is formed by drawing a metalplate of brass, aluminum alloy, etc. The fastener body 10 includes analmost disk-like base 20 and a hollow cylindrical post 30 which extendsupward from a center area of the base 20 concentrically. The top (34) ofthe post 30 (or the top face defined by the top (34)) is open as a topopening 30′. The post 30 has a fold-back portion 35 which is formed byfolding back the metal plate making the post 30 from the top 34 radiallyinward and downward. The top 34 of the post 30 which is the proximal endof the fold-back portion 35 is formed as a sharp annular edge(hereinafter referred to also as “top edge”) 34 to facilitate cuttingand piercing through a fabric c at the time of mounting of a button 50(see FIG. 4 etc.) to the fabric c as described in detail later. Thebottom of the post 30 is open as a bottom opening 30″ in the center areaon the lower surface of the base 20. The cover member 40 is attached tothe fastener body 10 so as to cover the base 20 from below. The bottomopening 30″ is closed by the cover member 40.

The post 30 (except for the fold-back portion 35) is divided into a postproximal portion 31 rising gradually from the base 20 and having curvedlongitudinal sectional (inner and outer) surfaces; a post barrel portion32 extending upward from the post proximal portion 31 while the outerdiameter of the portion 32 slightly reducing gradually and having linearlongitudinal sectional (inner and outer) surfaces; and a post distalportion 33 including the top edge 34 as mentioned above and having theouter diameter which expands radially outward from the upper end of thepost barrel portion 32. The outer diameter of the post distal portion33, as shown enlarged in FIG. 3, gradually expands upward from the upperend of the linear longitudinal sectional outer surface of the postbarrel portion 32 up to the maximum, and then slightly reduces to thetop edge 34 gradually. The diameter of the top edge 34 of the post 30 isgreater than the outer diameter of the post barrel portion 32throughout. The thickness of the post barrel portion 32, post distalportion 33 and fold-back portion 35 is gradually thinner from the lowerend to the upper end of the post barrel portion 32, and then, via thepost distal portion 33, from the upper end (proximal end) to the lowerend (distal end) of the fold-back portion 35, except for about the topedge 34 as the turn-round part of the fold-back portion 35. Because ofthe thickness getting thinner from the lower end of the post barrelportion 32 to the distal end of the fold-back portion 35 like this, aload as needed to turn down the fold-back portion 35 can decreaseleading to be a better workability compared with a constant thickness.With the fold-back portion 35, the thickness about the top edge 34increases since the post distal portion 33 and the fold-back portion 35overlap and their respective thickness is added.

The fold-back portion 35 includes, on its inner periphery, a firstinclined surface 35 a with a gentle inclination, the inner diameter ofwhich drastically decreases from the top edge 34 radially inward, and asecond inclined surface 35 b with a steep inclination, the innerdiameter of which somewhat decreases from the radially outer end of thefirst inclined face 35 a to the lower end of the fold-back portion 35.The first inclined surface 35 a forms the sharp edge 34 together withthe outer periphery surface of the post distal portion 33. The fold-backportion 35 is cut out upward from the lower end partially in a triangleform so as to facilitate decreasing the diameter toward the lower endeasier. The length of the fold-back portion 35 in the axial directionexceeds that of the post distal portion 33 and equals approximately ¼ ofthe height (the axial length) of the post 30 from the base 20.

The base 20 includes a base bottom 21 extending radially outward fromthe lower end of the post proximal portion 31 horizontally, and a baseflange 22 rising upward relative to the base bottom 21 radially outwardfrom the base bottom 21. The base flange 22 has a flange inclinedportion 22 a being inclined gradually upward and radially outward fromthe radially outer end of the base bottom 21, and a flange horizontalportion 22 b extending horizontally and radially outward from theradially outer end of the flange inclined portion 22 a. The cover member40 includes a disk-like, horizontal cover base 41 covering the lowersurface of the base bottom 21 including the bottom opening 30″ of thepost 30, and a curved outer periphery 42 turning back in a C-shapedcross-section upward from the radially outer end of the cover base 41 soas to wrap around a radially outer end part of the base 20, terminatingon the flange horizontal portion 22 b. The curved outer periphery 42rises upward beyond the flange horizontal portion 22 b of the base 20.

FIG. 4 shows a state where the button 50 (here, a decorative button isexemplified), the fabric c and the button fastener 1 are arranged in theup and down direction (the radial direction) when the button 50 isfastened to the fabric c. The button 50 and the button fastener 1 areone embodiment of a button structure in accordance with the presentinvention. In the state of FIG. 4, although not shown in the drawings,the button 50 is held by an up-and-down part of a well-known pressmachine, and the button fastener 1 is set on a lower die concentricallywith the button 50. The button 50 is a well-known one as formed bydrawing a metal plate. The button 50 includes a center projection 51projecting upward in a dome-shape; a peripheral side 55 turning backupward and radially outward from the lower end 52 of the projection 51and extending upward up to somewhat beyond the top of the projection 51while expanding its outer diameter radially outward, surrounding theprojection 51; and an annular flange 56 extending radially outward fromthe upper end of the peripheral side 55 while somewhat lowering, theradially outer end of the flange 56 being at the same height as the topof the projection 51. The projection 51 has a bottom opening 53 near atthe lower end of the projection 51. There is defined a post-receivingspace 54, which is a space for receiving the post 30 of the buttonfastener 1 through the bottom opening 53 when the button 50 is beingfastened to the fabric c and then deforming the post 30 to be fixed. Thelower end 52 of the projection 51, which is the turn-round part of theperipheral side 55, is a semicircular shape in longitudinal section, thediameter of the semicircular shape being the same length as thethickness of a double metal plate forming the button 50. The innerdiameter of the projection 51 or the diameter of the post-receivingspace 54 is at the maximum at a spot 54′ above the bottom opening 53,and somewhat decreases from the maximal diameter spot 54′ to the bottomopening 53 and then increases again to the lowest spot 52′ of the lowerend 52. That is, the bottom opening 53 is at slightly above the lowestspot 52′ of the lower end 52, and the inner diameter of the opening 53is at the minimum at the bottom opening 53 slightly above the lowestspot 52′. The diameter of bottom opening 53 is approximately the same asthat of the top edge 34 of the button fastener 1. The lower end 52 ofthe projection 51, as being a semicircular cross-section as mentionedabove, can effectively hold down the fabric c when the fabric c is cutby the top edge 34 of the button fastener 1 as described later.Therefore, the lower end 52 is hereinafter referred to also as“fabric-holddown 52.”

When the button 50 is fastened to the fabric c using the button fastener1, by lowering the button 50 from the state shown in FIG. 4, the fabricc is held between the button 50 and the button fastener 1 as shown inFIG. 5. After that, the post 30 of the button fastener 1 cuts andpierces the fabric c with the top edge 34 in the lead, and then goesinto the post-receiving space 54 of the button 50. At the timeimmediately before cutting the fabric c in FIG. 5, the fabric c is madethinner annularly by being compressed between the fabric-holddown 52 ofthe button 50 and the top edge 34 of the post 30 of the button fastener1, and the radially inner portion from the annularly compressed spot isextending into the post-receiving space 54 through the bottom opening53. From this state, the edge 34 relatively moves up to cut the fabricc, and at this time the first inclined surface 35 a of the fold-backportion 35 of the button fastener 1 can hold the posture of the fabric cwhile supporting the fabric c, enhancing the effectiveness of the edge34 and serving to help cut the fabric c smoothly by the top edge 34. Around piece c′ cut out by the edge 34 is received within thepost-receiving space 54.

The post 30, which has gone into the post-receiving space 54 through thebottom opening 53 of the button 50 after piecing the fabric c as shownin FIG. 7 is plastically deformed so as to decrease the diameter of thetop opening 30′ gradually while the edge 34 is guided upward along theinner surface of the projection 51. Finally, the post 30 is compressedin the axial direction and fixed as shown in FIG. 8. At the time of FIG.7, the fabric piece c′ is taken into the post 30 through the top opening30′ of the post 30, so the fabric piece c′ would not have an adverseeffect on the deformation of the post 30. Because of the post distalportion 33 being radially outward expanded, the fabric piece c′ can betaken into the post 30 smoothly. The fabric piece c′ in the post 30remains within the button fastener 1 since the bottom opening 30″ isclosed by the cover member 40. (See FIG. 8) As the fabric piece c′ doesnot go out of the fastener 1, a work to look for and remove fabricpieces c is unnecessary after the button 50 is mounted. In the FIG. 8state where the button-fastening is completed, the post 30 of the buttonfastener 1 is compressed along the inner surface of the projection 51 toconform to the shape of the post-receiving space 54, and thereby thepost 30 becomes undetachable from the post-receiving space 54. As aresult, the button 50 and the button fastener 1 are connected to eachother with the fabric c held therebetween. In the fastening completedstate, the top opening 30′ of the post 30 becomes closed, and the fabricpiece c′ remains in the compressed post 30. Further, the fabric c isfirmly held between the flange 56 of the button 1 and the curved outerperiphery 42 of the cover member 40 of the button fastener 1 and is madethinner due to the compression. Since the curved outer periphery 42 liesupward further than the flange horizontal portion 22 b which risesupward rather than the base bottom 21 of the base 20, the curved outerperiphery 42 can be close to the flange 56, which makes it possible tosurely fasten the button 50 to the fabric c as being thin.

FIGS. 9 to 11 are sectional views showing button fasteners 61, 71, 81 inaccordance with another embodiment of the present invention. Thesefasteners 61, 71, 81 comprise a fastener body 10 a, 10 b, 10 c and acover member 40 (this cover member is identical with that in the buttonfastener 1, so the same reference number is used). In the fastener body10 a, 10 b, 10 c, there are differences from the button fastener 1substantially only in their post distal portions and whether a fold-backportion exists. Therefore, in FIGS. 9 to 11, the same reference number20 is also used to the base as in FIG. 1 etc.

The post 90 of the fastener 61 as shown in FIG. 9 extends from theproximal end to the distal end linearly in longitudinal section whilethe outer diameter slightly decreases gradually. The post 90 has the topopening 90′. The post distal portion 93 does not expand radially outwardrelative to the post barrel portion 92, and a fold-back portion is notprovided. In the post 100 of the fastener 71 as shown in FIG. 10, thepost distal portion 103 expands radially outward with the outer diametergradually increasing the outer diameter upward from the upper end of thepost barrel portion 102. Thereby, the top opening 100′ enlarges, makingthe capture of the fabric piece c′ easily. The upper end of the post 100is formed as a edge 104, and the diameter of the edge 104 is larger thanthe outer diameter of the post barrel portion 102. A fold-back portionis not provided. The post 110 of the fastener 81 as shown in FIG. 11includes the post distal portion 113 which expands radially outwardrather than the post barrel portion 112 as with the fastener 1. The post110 is different from the fastener 1 only in the fold-back portions. Thefold-back portion 115 extends from the top edge 114 of the post 110radially inward and downward while gently inclining. In this case, whenthe post 110 is being deformed within the post-receiving space 54 at thetime of mounting the button 50 to the fabric c, although not shown inthe drawings, the fold-back portion 115 can open radially outward anddownward, through which the fabric piece c′ is taken into the post 110.The posts 90, 100, 110 of the fastener 61, 71, 82 include the samebottom openings 30″ as in the post 30 of the fastener 1.

FIG. 12 is an illustrative sectional view, similar to FIG. 8, showing astate where a decorative button 120, which is a different type from thebutton 50, has been fastened to the fabric c using the button fastener 1(this fastener is substantially the same as that in FIG. 1 etc., so thesame reference numbers as to the fastener 1 are used). The button 120includes a projection 121 projecting upward and an annular flange 126extending radially outward from the projection 121. There is defined apost-receiving space 124 in the projection 121. In the state where thebutton 120 has been fastened to the fabric c, the post 30 of the buttonfastener 1 is deformed and fixed within the post-receiving space 124,and the fabric c is held between the flange 126 of the button 120 andthe curved outer periphery 42 of the button fastener 1. Further, thefabric piece c″ is captured in the post 30. As a button fastener withrespect to the button 120, the fastener 61, 71, 82 can also be used.

FIG. 13 is an illustrative sectional view, similar to FIG. 8, showing astate where a button 130 as a male snap has been fastened to the fabricc using the button fastener 1 (this fastener is substantially the sameas that in FIG. 1 etc., so the same reference numbers as to the fastener1 are used). The button 130 includes a projection 131 projecting upward,which detachably engages with a depression of a female snap (not shown),and an annular flange 136 extending radially outward from the projection131. There is defined a post-receiving space 134 in the projection 131.In the state where the button 130 has been fastened to the fabric c, thepost 30 of the button fastener 1 is deformed and fixed within thepost-receiving space 134, and the fabric c is held between the flange136 of the button 130 and the curved outer periphery 42 of the buttonfastener 1. Further, the fabric piece c″ (since it is the same as inFIG. 12, the same reference number is used) is captured in the post 30.As a button fastener with respect to the button 130, the fastener 61,71, 82 can also be used.

DESCRIPTION OF REFERENCE NUMBERS

-   1, 61, 71, 81 button fastener-   10, 10 a, 10 b, 10 c fastener body-   20 base-   22 b flange horizontal portion-   30, 90, 100, 110 post-   30′, 90′, 100′, 110′ top opening-   30″ bottom opening-   31 post proximal portion-   32, 92, 102, 112 post barrel portion-   33, 93, 103, 113 post distal portion-   34, 94, 104, 114 upper end of post-   34, 104, 114 edge-   35, 115 fold-back portion-   35 a first inclined surface-   35 b second inclined surface-   40 cover member (shell)-   42 curved outer periphery-   50, 120, 130 button-   51, 121, 131 projection-   52 lower end of semicircular part (fabric-holddown)-   53 bottom opening-   54, 124, 134 post-receiving space-   56, 126, 136 flange-   c fabric-   c′, c″ fabric piece

1. A button fastener for fastening a button to a fabric, comprising: afastener body including a disk-like base and a post which extends upwardfrom a center area of the base concentrically; and a cover member whichis attached to the fastener body so as to cover the lower surface of thebase; wherein said base includes a base bottom adjacent to the post anda base flange rising upward relative to the base bottom radially outwardfrom the base bottom; wherein said cover member includes a curved outerperiphery curving from the lower surface side of the base and thenrising upward beyond the base flange of the base.
 2. The button fasteneraccording to claim 1, wherein said post is hollow and cylindrical andincludes a top opening which is open at the upper end of the post and abottom opening which is open in a center area of the base.
 3. The buttonfastener according to claim 1, wherein said upper end of the post isformed as a edge which is able to cut the fabric against the button whenthe button is fastened to the fabric.
 4. The button fastener accordingto claim 3, wherein said post includes a fold-back portion which isfolded back radially inward and downward from the upper end of the post.5. The button fastener according to claim 4, wherein said fold-backportion includes, on its inner periphery, a first inclined surface whichgently inclines radially inward and downward from the upper end of thepost and a second inclined surface which steeply inclines radiallyinward and downward from the radially inner end of the first inclinedsurface.
 6. The button fastener according to claim 1, wherein said postincludes a post proximal portion adjacent to the base, a post distal endincluding the upper end, and a post barrel portion linearly extendingbetween the post proximal portion and the post distal portion, whereinthe outer diameter of the post distal portion expands radially outwardfrom the upper end of the post barrel portion, and the maximal outerdiameter of the post distal portion is greater than the outer diameterof the post barrel portion.
 7. The button fastener according to claim 6,wherein the thickness of the post barrel portion, post distal portionand fold-back portion is gradually thinner from the lower end to theupper end of the post barrel portion, and then, via the post distalportion, from the upper end to the lower end of the fold-back portion,except for about the upper end of the post as the turn-round part of thefold-back portion.
 8. A button structure composed of a button and abutton fastener for fastening the button to a fabric, the buttonfastener comprising: a fastener body including a disk-like base and apost which extends upward from a center area of the base concentrically;and a cover member which is attached to the fastener body so as to coverthe lower surface of the base; wherein said base includes a base bottomadjacent to the post and a base flange rising upward relative to thebase bottom radially outward from the base bottom; wherein said covermember includes a curved outer periphery curving from the lower surfaceside of the base and then rising upward beyond the base flange of thebase; wherein said button includes a projection projecting upward and anannular flange extending radially outward from the projection; whereinsaid projection defines a post-receiving space in the interior thereoffor receiving, deforming and fixing the post which has pierced thefabric; wherein said flange, in the state where the button has beenfastened to the fabric with the post fixed in the post-receiving space,faces the curved outer periphery with the fabric held between the flangeand the curved outer periphery.
 9. The button structure according toclaim 8, wherein said post is hollow and cylindrical and includes a topopening which is open at the upper end of the post and a bottom openingwhich is open in a center area of the base.